Irreversible and reversible blockade of IMR32 calcium channel currents by synthetic MVIIA and iodinated MVIIC ω-conopeptides
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The actions of two ω-conopeptides on high-voltage-activated calcium channel currents in differentiated human neuroblastoma IMR32 cells were investigated. Similar to the previously reported action of ω-conopeptide GVIA, ω-conopeptide MVIIA irreversibly blocks IMR32 HVA calcium channel currents at low concentrations. Unlike GVIA action, however, novel w-conopeptide SNX-260 (iodinated MVIIC) reversibly blocks these currents, also at low concentrations, with an IC50 near 50 nM. Different ω-conopeptides may be potent blockers of HVA calcium channel currents yet act either reversibly or irreversibly in a single cell.
Key WordsCalcium Channel ω-conotoxin IMR32
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